The present invention relates to magnetic data storage tape systems. More particularly, the present invention pertains to methods and systems for positioning read/write heads on magnetic data storage tape using magnetic reference indicator marks in connection with optical servo positioning.
Magnetic data storage systems (e.g., disk, tape) which utilize media having magnetic servo tracks are generally known in the art. These systems utilize a magnetic pattern having a fixed relationship to one or more data tracks to servo position a transducing or read/write head over the data track(s). An example of this sort of system is described in U.S. Pat. No. 5,689,384 to Albrecht et al., issued Nov. 18, 1997.
Optical servo systems utilizing optical servo tracks provide an alternative to magnetic servo systems. Optical servo systems utilize a series of optical features located relative to the data storage tracks to servo position a magnetic read/write head over the desired data track. Optical servo systems are advantageous over magnetic servo systems in that they can potentially free-up a greater portion of the media surface for magnetic data recording. Examples of optical servo systems can be found in U.S. Pat. Nos. 4,958,245 issued to Roth et al., and 5,563,864 issued to Kobayashi et al.
Some disk drive systems utilize a magnetic reference on the disk to adjust the position of an optically-servoed read/write head. For example, see U.S. Pat. No. 4,935,835 to Godwin et al. However, these systems are directed to disk drives.
To provide an optical servo system for use with data storage tape that overcomes these problems, optical servo systems are provided where the tape includes magnetic reference indicator marks. In one embodiment, a method of positioning a magnetic read/write head on a magnetic data storage tape is provided. The method includes a magnetic data storage tape having at least one magnetic data storage track extending along a length of the tape, at least one optical servo pattern distributed along the length of the tape, and at least one magnetic reference indicator mark located along the magnetic data storage track. A head mechanism is also provided where the head mechanism has a magnetic head and an optical head. The method includes moving the magnetic data storage tape relative to the head mechanism in a transducing direction and positioning the magnetic head in a translating direction over a selected magnetic data storage track by detecting a selected optical servo pattern with the optical head. The method further includes detecting a first magnetic reference indicator mark and adjusting the position of the magnetic head over the selected magnetic data storage track based on the first magnetic reference indicator mark.
In another embodiment, a magnetic data storage tape is provided. The tape includes at least one magnetic data storage track extending along a length of the tape, at least one optical servo pattern distributed along the length of the tape; and at least one magnetic reference indicator mark located along the magnetic data storage track.
In still another embodiment, an information handling system is provided having a tape drive with an optical servo system. The optical servo system includes a head mechanism having a magnetic head and an optical head wherein the optical head is adapted to maintain the position of the magnetic head over a data track on a magnetic tape as the magnetic tape moves relative thereto. The magnetic head is adapted to calibrate the head mechanism by reading one or more magnetic reference indicator marks located along the tape. The system also includes an information processing device operatively coupled to the tape drive.
Advantageously, the present invention provides an optical servo system for use with a magnetic tape drive wherein the optical servo system may be recalibrated to correct for dimensional fluctuations of the tape drive components to maintain consistent, accurate positioning of the read/write heads relative to the tape.